中高樓結構機率式倒塌風險評估法之應用研究

Probabilistic assessment of seismic performance and collapse risk for mid-rise buildings

謝瑋桓(Wei-Huan Hsieh) ； 盧煉元(Lyan-Ywan Lu) ； 蕭輔沛(Fu-Pei Hsiao) ； 湯宇仕(Yu-Shi Tang) ； 黃尹男(Yin-Nan Huang)

《結構工程》 33卷2期 (2018/06) Pp. 89-120

https://doi.org/10.6849/SE.201806_33(2).0005

摘要

都會區由於地狹人稠之故，建築物大多屬於中高樓結構，這些結構若於地震中倒塌或受損所造成的地震災害將不容小覷。因此對於老舊或因設計施工不良具潛在危險性之中高樓建物，吾人實有必要建立一套合理的耐震評估方法，以作為工程實務上篩檢與補強之依據。然而，現行建物評估法大多屬於定量式(deterministic)的非線性靜力側推分析法，此法對於低矮樓房或有其準確性，但卻不易預估中高樓結構高頻振態之反應，亦未能計及震波與設計及施工中所涵有的諸多不確定因子，因此評估結果有可能不夠保守。有鑑於此，本文旨在研議一實用之機率式建物倒塌耐震評估方法與流程，該方法乃結合美國FEMA P-58之倒塌易損分析法、非線性增量式動力分析法與地震危害度分析法等，以計及結構在強震下的非線性動態特性及地震力的不確定性等項因子。惟因FEMA P-58對於建物倒塌的判定準則與倒塌性能指標的選擇並無明確的建議。因此，本文乃參採PEER-TBI與ASCE 41-13技術報告針對RC構造建議二項倒塌判定準則，分別稱為「總體結構」與「局部構件」倒塌判定準則。而在倒塌性能指標的訂定方面則參採ASCE 7-10及FEMA P695建議之倒塌機率容許值，亦即：「最大考量地震力之倒塌機率」小於10%及「50年內倒塌超越機率」小於1%，作為判定建物是否有倒塌疑慮之標準。其中，前者之最大考量地震力可採用我國設計規範之值，十分方便實務之應用；而後者則須配合工址所在之地震危害度曲線加以計算，有利建物所有人作為承擔風險決策之用。最後，再以一實際倒塌的中高樓建物案例說明本文所建議倒塌性能評估法之執行程序。

關鍵字

中高樓建築 ； 機率式評估法 ； 耐震性能評估 ； 倒塌易損分析 ； 風險評估 ； 增量動力分析 ； 非線性歷時分析

並列摘要

Mid-rise buildings, which are usually heavily populated, are very common structures in urban areas. The casualty and social impact caused by the collapse of mid-rise buildings in an earthquake can not be overestimated. Therefore, developing suitable assessment methods to identify the buildings with high collapse risk becomes a critical issue. Even though traditional seismic assessment methods, which usually employ nonlinear static pushover analysis, have been successfully applied to regular low-rise buildings, these methods are unable to reflect higher-mode effect on the responses of mid-rise buildings. Furthermore, a traditional approach usually leads to a deterministic result that could not account for the uncertainty in seismic motions and structural responses of a mid-rise building, which is usually more complicated and involves more structural uncertainties than a low-rise building. To this end, this paper presents a procedure and methodology to assess the collapse risk of a mid-rise building. This methodology is developed based on the collapse fragility analysis proposed by FEMA P-58, the collapse criteria proposed by PEER-TBI and ASCE 41-13, and acceptance criteria suggested by ASCE 41-13 and FEMA 356. To establish the fragility curves, this approach employs nonlinear time history analysis together with the method of incremental dynamic analysis (IDA) to estimate structural response parameters. Finally, for demonstration, the proposed assessment method is applied to assess the collapse risk of a mid-rise building that collapsed in an earthquake.

並列關鍵字

Mid-rise building ； seismic performance assessment ； probabilistic assessment ； collapse fragility analysis ； risk assessment ； incremental dynamic analysis ； nonlinear time history analysis